中文摘要：

提出了一种基于白光干涉术测量低锐度光纤外腔Fabry-Perot干涉仪（EFPI）的方法。用宽带光源注入F-P腔，在接收端用一高锐度的可调谐光纤F-P滤波器对EFPI的反射光谱进行扫描，获得了周期性变化的光谱输出。为了测量出EFPI的腔长，对光谱信号进行傅里叶变换，得到光谱的周期，由此求出EFPI的绝对腔长。证明了用低锐度EFPI的测量准确度由腔长决定。F-P腔越长，测量准确度越高。在腔长分别是200μm，400μm和600μm时，测量的腔长与实际腔长相同。

英文摘要：

The white light interferometry for the measurement of low-finesse extrinsic Fabry-Perot interferometer（EFPI） is reported. A broadband light is injected into EFPI, and the reflected light is scanned by another high-finesse tunable Fabry-Perot filter, the periodic spectra of EFPI can be obtained. To measure the cavity length, the spectra are fast Fourier transformed, the absolute length of cavity can be calculated by using the periodic spectra. The measuring accuracy is limited by the length of cavity. The longer cavity has higher measuring accuracy. When the length of cavity are 200 μm, 400 μm, and 600μm respectively, the measured results are agree with the actual length of the cavity.